LUR crashes in "stupid type conversions" when compiling module

Compiling with:

sac2c crudscan.sac -maxoptcyc 1 -d treecheck -chkfreq 4 -v4

crashes in LUR's GetLoopIdentifiers, near "stupid type conversions".

module UTRepresentation;
use Array:{shape,genarray,<,+,++,-,*,sum,sel,modarray};
export {NOTmain};

inline int mpybslXII(int[.] y)
{ /* Scan of vector */
 size = shape(y);
 arg = genarray(size,1);
 z = 42;
 for ( i=1; i<size[[0]]; i++) {
    z = z + 4 * 3;
 }
 return(z);
}

int NOTmain ()
{
 z=mpybslXII( [2,3,1]);
 return(z);
}

Compiled with:

rbe@boa:~/JimBrown$ sac2c -V
sac2c 1.3.3-MijasCosta-583-g93687
build-type: DEBUG
built-by: "sac" at 2021-05-03T11:17:13